A bidirectional AC-to-DC and DC-to-AC circuit includes a first inductor-capacitor (LC) circuit connected to an AC power source, a transistor synchronized with the AC power source signal, a second LC circuit electrically connected to the synchronized transistor and the first inductor-capacitor circuit, a high-frequency switching transistor electrically connected to the second inductor-capacitor circuit and a direct current (DC) load, and a controller connected to the high-frequency switching transistor. The controller identifies an error between a measured DC output signal and a predetermined DC output signal that is applied to the DC load, and adjusts a duty cycle of a pulse width modulation (PWM) switching signal for the high-frequency transistor to reduce the identified error.

A controller for determining the duty-ratio for a pulse width modulator of a converter includes an inner current loop, an outer voltage loop and a multiplier with an input voltage feed forward to connect both loops. A prediction unit determines a correction signal i.sub.cor that is added to the reference current i.sub.ref by means of an adder and it further determines a sample correction signal to correct the current samples in the current loop. This error-controlled duty-ratio prediction with sample correction results in an improved total harmonic distortion as well as in an improved power factor of the converter.

The present invention discloses a hybrid transformation system based on three-phase voltage type PWM rectifier and multi-unit uncontrolled rectifier. The hybrid transformation system mainly consists of a three-phase reactor (L), a three-phase voltage type PWM rectifier module, an N-unit three-phase uncontrolled rectifier bridge module group, capacitors (C0-CN) and a DSP control circuit. An input end of the three-phase voltage type PWM rectifier module is in parallel connection with an input end of each three-phase uncontrolled rectifier bridge module. The three-phase voltage type PWM rectifier module may work in to situations, with load or without load, and the three-phase voltage type PWM rectifier module just does reactive power compensation when working without load. All modules of the three-phase uncontrolled rectifier bridge module group may work in to situations, with loads independently or all the outputs are in parallel connection and with a same load. The hybrid rectifier system has advantages such as unity input power factor, grid side current low harmonic, high power output, low cost, easy control, and etc.

Systems and methods for enhancing peak power capability and hold-up time in a resonant converter having a LLC topology may include a couple choke transformer circuit that may control an inductance of the couple choke transformer circuit and improve power efficiency of the resonant converter. The resonant converter may also include a resonant tank circuit that may provide improved peak power delivery of the resonant converter. The resonant converter may further include a resonant tank control circuit to control the resonant tank circuit and may increase the peak gain of the resonant converter, increase a voltage range of the input voltage, and extend a hold-up time of the input voltage when an AC power failure occurs.

An inverter apparatus is provided for converting direct current to alternating current. The inverter apparatus includes a boost converter coupled between a power source and a bypass circuit, and a power inverter coupled between the bypass circuit and a load to generate an output voltage. The output voltage is powered by the power source directly via the bypass circuit without activating the boost converter when the output voltage is smaller than a threshold voltage. The output voltage is powered by the power source boosted by the boost converter when the output voltage is larger than the threshold voltage. High efficiency is achieved by bypassed the boost converter.

A primary circuit and a secondary circuit each have a switching element, each operate as a power conversion circuit while the switching element is activated, and each operate as a rectifier circuit while the switching element is deactivated. While a generator provided at the primary side of a first power conversion device is stopped, a controller activates the switching element of the secondary circuit and deactivates the switching element of the primary circuit. Accordingly, the first power conversion device converts electric power input from the secondary side and supplies electric power for causing the generator to operate. While the generator is operated, the controller activates the switching element of the primary circuit and deactivates the switching element of the secondary circuit such that the first power conversion device converts electric power supplied from the generator and outputs the converted electric power to the secondary side.

The disclosure reduces the occurrence of an inrush current upon electrical connection of a storage cell, allowing immediate use. A power supply apparatus is configured to convert DC power from a solar cell and a storage cell into AC power and includes: a first capacitor disposed between the solar cell and the storage cell; and a controller configured to charge the first capacitor with power from the solar cell or a power grid and, after a first voltage of the first capacitor exceeds a second voltage of the storage cell, to electrically connect the storage cell with the first capacitor.

A DC/DC flyback converter that exhibits reduced switch and transformer voltage stresses in comparison to known flyback converters. The flyback converter also employs soft switching. Embodiments of such flyback converters may be used, without limitation, in electric vehicles and hybrid electric vehicles. A front-stage of the flyback converter comprises a DC/AC step-down circuit that may be separately used for various purposes.

A DC/DC flyback converter that exhibits reduced switch and transformer voltage stresses in comparison to known flyback converters. The flyback converter also employs soft switching. Embodiments of such flyback converters may be used, without limitation, in electric vehicles and hybrid electric vehicles. A front-stage of the flyback converter comprises a DC/AC step-down circuit that may be separately used for various purposes.

A power distribution system is described. The system includes a main ac busbar and an emergency ac busbar. A hybrid drive system includes an induction electrical machine and a prime mover, the rotor of the electrical machine and the driving end of the prime mover being mechanically coupled to a load by means of a mechanical linkage such as a gearbox. The system includes a first active rectifier/inverter having ac input terminals electrically connected to the main ac busbar, and dc output terminals. The system includes a second active rectifier/inverter having dc input terminals electrically connected to the dc output of the first active rectifier/inverter by a dc link, and ac output terminals electrically connected to the induction electrical machine. A blackout restart system includes a rectifier having ac input terminals selectively electrically connectable to the emergency ac busbar and dc output terminals selectively electrically connectable to the dc link.